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The University of Southampton
Ocean and Earth Science, National Oceanography Centre Southampton

Research project: GGREW - Greenhouse Gas Removal by Enhanced Weathering

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Weathering of rocks at the Earth’s surface is a natural process that converts atmospheric CO2 into benign forms of carbon, including carbonate minerals. This project aims to speed up this process to reduce levels of CO2 in the atmosphere.

To limit the increase in global temperature to less than 2 °C, “negative emissions”, or the active removal of carbon dioxide from the atmosphere, are required. Weathering, the chemical breakdown (dissolution) of rocks at the Earth’s surface, is a natural process that converts atmospheric carbon dioxide into carbonate minerals or hydrogen carbonate and carbonate ions (“alkalinity”). If the weathering process can be speeded up, or enhanced, then levels of atmospheric carbon dioxide would fall.  

Mining of precious commodities, such as diamonds and gold, provides a continuous supply of freshly ground up rock material which, under the right conditions, could be easily weathered, removing atmospheric CO2 in the process.

Fundamental questions 

Our project aims to provide critical knowledge to answer the following questions: 

  • Are rocks left over from extracting precious metals suitable for capturing carbon dioxide on human timescales? 
  • Are there low-cost engineering solutions that can be used to accelerate the weathering process? 
  • How much carbon dioxide could potentially be captured? 

We are addressing these questions through identification of the most easily weatherable mine waste materials, the testing of physical, chemical and biological methods for speeding up weathering kinetics, and an investigation into the availability of (suitable) rock materials at mine sites on a national and global scale. 

Specific objectives 

Our work will assess the technical, environmental and societal challenges involved in assessing the potential of enhanced weathering as a carbon sequestration technology. We will do this through: 

1. Assessment of the worldwide potential of the mining sector for carbon dioxide removal through enhanced weathering based on a global industry desktop study. 

2. Development of a detailed dataset for the enhanced weathering and carbon dioxide storage potentials of chemically-favourable mine waste material in South Africa. 

3. Characterisation of available rock waste material (quantity, location, mineralogy, geochemistry, and grainsize) and naturally occurring microbial communities naturally thriving in a platinum mine in South Africa.  

4. Laboratory experimentation and assessment of the rates of break-down of representative rock waste material. 

5. Developing a biotechnological approach to harness naturally occurring microbial processes to enhance weathering rates of mine waste material. 

South Africa study site 

South Africa is one of the world’s largest producers of mine wasted material. Each year, mining operations move, process and store millions of tonnes of rocks. We are exploring how the waste rock material can be better managed to maximise the potential for sequestering atmospheric CO2.  

 

Principal Investigator: Professor Rachael James

Funding dates: July 2017 - June 2021

Funding provider: The GGREW project (NE/P019536/1) is supported by NERC, the Engineering & Physical Sciences Research Council (EPSRC), the Economic & Social Research Council (ESRC), and the Department for Business, Energy & Industrial Strategy (BEIS), with in-kind contributions from the Met Office Hadley Centre and the Science & Technology Facilities Council (STFC).  

Programme Website: http://www.ggrprogramme.org.uk/

 

 

Rock ore prior to processing at a mine site
Rock ore prior to processing at a mine site
Crushed & ground rock material stored at the mine in ‘tailings ponds'
Crushed & ground rock material stored at the mine in ‘tailings ponds'
Processing of the ore produces CO2
Processing of the ore produces CO2
Microbiological sampling at a tailings pond
Microbiological sampling at a tailings pond
Enrichment microbial cultures from a mine site in South Africa
Enrichment microbial cultures from a mine site in South Africa
Experimental set up to determine the reactivity of mine waste material
Experimental set up to determine the reactivity of mine waste material
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SEM image of a glassy mine waste product following processing
SEM image of a glassy mine waste product following processing
Examination of in-situ bedrock in South Africa
Examination of in-situ bedrock in South Africa

Related research groups

Geochemistry
Marine Biogeochemistry
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